Crossbar line switch



' f 1,551,190 I E. a. CRAFT CROSSBAR LINE SWITCH nets-Sheet Filed April 20. 1921 2 Aug. 25, 192 5.

E. B. CRAFT CROSSBAR LINE swxwcn and A ril 20. 192;

2 Sheets-Sheet 2 [award 5. C/wfzf Patented Aug. 25, 1925.

UNITED STATES PATENT OFFICE.

EDWARD B. CRAFT,.OF HACKENSACK, NEW JERSEY, ASSI GN OR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

oRossBAR LINE SWITCH.

Application filed April 20, 1921. Serial No. 462,991.

operate to further extend the desired con nections, and in case of semi-automatic sys terns, to operators positions from which points the desired connections are further extended by the operators. The present invention relates more particularly to line switches'of the crossbar type, in which are provided two intersecting groups of operating bars, the bars of one group being each associated with a subscribers line, and those of the other group each associated with a trunk, the joint operation of a bar in each group being effective to establish a connection between the subscribers line associated with one operated bar, and the trunk associated with the other operated bar.

One object of this invention is the provision of a cross bar line switch structure, which is economical to manufactureand adapted to render continuous satisfactory service. Another object is the, provision of a line switch having a terminal bank, on which repairs and replacements of defective parts may be made with the smallest amount of interference of service to the subscribers.

i In accordance with the above objects one feature of the present invention consists in a terminal bank comprising a plurality of self-contained line conductor units and a plurality of self-contained trunk conductor units, each of which is independently removable fromthe bank, thereby making it possible to quickly remove and replace any member which may become defective without in any way interfering with the others. Another feature consists in a unique plunger mechanism whereby the aforementionedline conductor units and trunk conductor units are brought into engagement. Other features of the invention will be brought out in the detailed description hereinafter.

I In the accompanying drawings, Figure 1 is a skeletonized perspective view of the line switch, showing only such parts as are necessary to an understanding of the invention.

Figure 2 is a detailed view showing in part, three trunk bars and two line bars, together with operating members associated therewith, and is intended to illustrate the mechanism employed for operating the trunk bars.

Figure 3 is a cross sectional view taken along the line 33 of Figure 2, illustrating two sets of operating plungers and push rods together with their associated bank contact springs. Some of the details shown in Figure 3 have been omitted from Figure 2 for the sake of clearness.

Line switches are usually arranged to accommodate 100 subscribers lines, and are provided with from 10 to 20 trunk connections, depending upon the traflic requirements in the area served. The present switch does not differ in this respect from other line switches of the same character.

The actual number of trunks and subscribers lines provided for is immaterial, however, toan understanding of the present invention.

Referring to Figure 1, there are shown two trunk units 4 and two line units 5 comprising parts of the terminal bank. The entire bank would include as many trunk units as there are trunks required to serve a switch, and as many line units as there are subscribers lines associated with the switch. Ordinarily, then, there would be 100 line units and from 10 to 20 trunk units. Each'trunk unit 4.- comprises four fiat metal strips 4, 4 ,4 and 4". These metal strips are insulated one from the other, and assembled into a self-contained unit which is mounted on a suitable supporting frame, from which it may be readily removed. Each metal strip of the trunk units is provided with a plurality of lugs 4 4 P and 4 There are as many of these lugs on each metal strip as there are line units (ordinarily 100).

The line units 5 each comprise a plurality of flat metal strips 5, 5 5 and 5*, insulated one from the other and assembled into a self-contained unit, which is mounted on the supporting frame with the trunk units, and like the latter is readily removable therefrom. The supporting frame for the trunk and line units is not shown on the drawings as it is thought this detail will be readily understood without illustration.

Each of the line unit conductors is provided with a plurality of flexible contact springs 5", 5, 5 ant 5 which are operably associated with the lugs 1 1, etc. of the trunk units, as is clearly shown in Figure 1. For each set of contact springs 5 5, etc. there is provided a push rod 6 mounted in suitable hearings (not shown) and provided with a head of insulating n'iaterial G. The push rods are adapted to be moved longitudinally in their bearings for operating the contact springs to effect connections with the lugs 4- 4:, etc. of the trunk units.

For .each subscriber-s line there provided a line bar 7, each 01'? which is associated with one of the line units 5. The line bars are n'iounted in suitable bearings, (not shown) in which they may be moved longitudinally. The two line bars shown in Figure 1 are in normal position, where they are held by the springs 13. Each line bar is provided with a plurality of plungers 10, corresponding in number with the trunk units. Each plunger is associated with a push rod (5, but is rori'nally out of operable relation therewith, as illustrated in Figure 1. An eleci romagnet 9 with its armature 8 is operably associated with each line bar, and adapted upon energization to move its line bar longitudina-illy against the tension of spring as, to a position wherein the plungers 10 are in alignment with their associated push rods 6. When a line bar is thus operated it is obvious that the subscribers line associated therewith may be connected to any one of the trunks by operating the appropriate plunger 10. The calling subscriber must be connected to only one trunk, and it must be ascertained in advance that this trunk is an idle one. The means whereby this is accomplished will be described.

For each trunk there is provided a trunk bar 11 mounted in suitable bearings (not shown) and adapted to be moved longitudinally. Each trunk bar is associated with one of the trunk units 4. There are two trunk bars shown in Figure 1, the one at the leftbeing shown in its normal position, and the one at the right in its oit-normal or preselected position. Each trunk bar is provided with a plurality of plunger-s 12 corresponding in number with the line bars. Each plunger 12 is associated with one, only, of the line bar plungers 10. The associated plungers are normally out of alignment with each other, but may be brought into alignment by conjoint operation of their respective trunk and line bars. The trunk bar at the right of Figure 1 being in its preselected or oil-normal position, it will be seen that a movement of either of the line bars will bring one of the plungers thereon into alignment with its associated trunk bar plunger. The two plungers thus brought into align ment will also be in line with their asso ciated push rods 6, and it is evident that a longitudinal movement of the trunk bar plunger 12 toward the terminal bank will be transmitted through the medium of the line bar plunger 10 to the push rod 6 which will move its associated contact springs into engagen'ient with the trunk unit lugs. In order that only one set of plungers may be brought into operable relation at any one time, provisions are made whereby only one trunk bar may be out of its normal position at a time.

An operating member 15 is slidably mounted on rods 16. Only one of the rods 16 is shown, but it will be understood that one ot these is provided at each corner of the operating n'ieniber. The operating member 15 con'iprises cross members 15 and vertical members 15 ()n the cross members 1:? are the lugs 17, each of which is associated with one of the trunk bar plungers 12. It will be seen that the lugs 17 asso ciated with the plungers 12 ot' the trunk bar at the rightof Figure 1. are in line therewith. A movement of the operating member toward the tern'iinal bank will therefore cause the plunger on the preselected trunk bar to be operated. The means provided for actuating operating member 15 will be described hereinafter.

Associated with each trunk bar is a locking plate 18, mounted in suitable bearings (not shown) and adapted to be moved longitudinally against the tension of spring 44 by armature 20 of electromagnet 19. Each locking plate is provided with a plurality of apertures 18, through which the plunger rods 6 associated therewith extend. Immediately following the actuation oi a push rod 6 to establish a connection, the locking plate 18 associated therewith is moved longitudiiilally by the armature 2O oi electromagnet 19, which is held energized throughout the duration of the call. The collar 6" of the operated push rod is engaged by the locking plate when the latter is operated, and the push rod is thereby held in its operated position. The locking bar at the left of Figure 1 is shown operated, and the lowermost push rod associated therewith is locked in its operated positicn.

The means for preselecting and operating the trunk bars will now be described. A shaft 23 journaled in suitable bearings (not shown) is movable longitudinally by electromagnet 38 and its armature 39, and is adapted to be rotated by a ratchet wheel 24 actuated by stepping pawl 25 on the armature 26 of motor magnet 27. On the right hand end of shaft 23 there is insulatively mounted a contact ring 31, to which is attached a contact brush30, both of which are rotatable with the shaft and slidably mounted thereon. The brush 45 makes contact with the ring 31. A commutator comprising an annulus of insulating material 32 and contact studs 33 is mounted by any suitable means on the frame of the switch in operable relation to the contact brush 30. Each rotary step of shaft 23 advances contact brush 30 from one contact stud 33 to the succeeding one. A disc 34 is securely mounted on shaft 23 and is rotatable and longitudinally movable therewith. A forked lever 35 secured to shaft 36 engages disc 34 and transmits the longitudinal movement of shaft 23 to the lever 37 which in turn actuates operating member 15. A longitudinal movement of shaft 23 in the direction indicated by the arrow Figure 1 will effect a movement of operating member 15 toward the terminal bank, the object of which, as already stated, is to effect operation of plungers 12. While only one of the operating links comprising levers35 and 37 and shaft 36 are shown, provisions would actually be made whereby the four corners of the operating member 15 would be movable simultaneously. The shaft 36 would in fact vbe extended upwardly, and another lever 37 attached thereto for the upper left hand corner of the operating lever, and another complete set comprising disc 34:, levers 35 and 37, and shaft 36 would be provided for the right hand side of the operating member.

For lifting the trunk bars out of normal into their preselected positions, bell cranks 28 5 are provided, one for each trunk bar. These bell cranks are each associated with a cam 29 on shaft 23, there being one cam for each bell crank. The several cams 29 are disposed in different angular positions around the shaft so that only one cam is in operable relation to its associated bell crank 28 at any one time. The longitudinal movement of shaft 23 in the direction indicated by the arrow is ineffective to move the trunk bars, as will be clear from an examination of Figure 2, the operation of one of the bell cranks 28 byits cam 29 being there illustrated. It will be seen that the cam in its movement to the right merelywithdraws the horizontally projecting arm of the bell crank from the lower end of the trunk bar, the latter being restrained from further downward movement by means which are not shown.

he cam in its movement to the right passes by the bell crank, allowing the latter to return to its normal position, but upon its return movement to the left the cam again engages the bell crank and operates it to lift the trunk bar.

The rocker member 21 is mounted by means of pivots 21 (one at each end) in suitable bearings (not shown) and is provided with a plurality of catches 21 (one for each trunk bar). Each trunk bar is provided with a lug 11' having an angular face, which upon upward movement of the trunk bar engages the angular face of its associated catch 21 and rotates the rocker member against the tension of spring 22. The trunk bar which was previously moved into its preselected position is released by the above described rotary movement of the rocker member, whereupon it drops back to its normal position. The lug 11' of the trunk bar, being moved upwardly, is engaged by its associated lug 21 as soon as the former passes the point of the latter, and is thereby held in its preselected position. It is obvious from the above description that only one trunk bar can be in its preselected position at any one time.

A description of the operation of the switch commencing with the initiation of a call and proceeding through the several steps will now be given. Upon the subscriber A lifting his receiver from the hook, a circuit is established from grounded battery through the electromagnet 9, conductor 40, back contact and inside armature of relay 4-1, conductor 42, line L through the subscribers telephone, line L conductor 15, outside armature and back contact of relay 41 to ground. Electromagnet 9 is energized and pulls up its armature 8, which moves its associated line bar 7 against the tension of spring 43 to position the plunger-s 10 thereon in line with their associated push rods 6.

The trunk bar 11 at the right hand side of Figure 1 having been previously moved into its preselected position, the uppermost plunger 12 shown thereon is then in alignment with its associated plunger 10 on the line bar.

In Figure 3, the uppermost line bar plunger 10 and its associated trunk bar plunger 12 are shown in alignment with their associated push rod 6. The lower line bar plunger in the same view is in its normal position and is therefore not in line with the trunk bar plunger with which it is associated. Electromagnet 9, upon pulling up its armature, establishes a circuit from ground through contact springs 16 and 47, conductors {t8 and 49, contact springs 50 and 51, conductors 52, 53 and 54 to the left hand winding of differential relay 55 to battery and ground. A branch of this circuit extends through electromagnet 38, conductor 59, contact springs 58, 57 and 56 to battery and ground. Relay 55 and electromagnet 38 are both energized and relay 55 pulls up its armature establishing a ground for the circuit of electromagnet 38 for holding the latter energized after the contact between contact springs and 51 is broken thereby ensuring that armature 39 will complete its forward movement. WVhen armature 39 reaches the limit of its forward movement, contact spring 51, having first disengaged contact spring 50, engages contact spring 75 and a circuit is thereupon established through both windings of differential relay 55. Since its two windings are opposed, relay 55 is deenergized and its armature falls back, thereby breaking the circuit through electromagnet 38 whereupon the latter is deenergized and its armature 39 together with shaft more back to normal.

The longitudinal movement of shaft 23 in the direction of the arrow on Figure 1, imparted by armature 39 upon the previously mentioned energization of magnet 38 effects a forward movement of operating member 15 through the medium of discs 34:, levers 35, .hafts 36 and lovers 37 to operate the plungers at the upper right hand corner of Figure 1, whereby a connection is established between the contact springs 5", 5 5 and 5 of the line unit 5 with the lugs 41-, 4, 1" and 4 of the trunk unit 4: shown on the upper right hand corner of F i gure 1. A circuit is thereupon established from grounded battery through the winding of repeating coil 60, conductor 61, trunk unit conductor 4?, contact spring 5, line unit conductor 5, line L,, through the subscribefs telephone set, line L,, line unit conductor 5 line unit contact spring 5, trunk unit conductor 41-", conductor ('32, relay 63, conductor 64-, winding 60 of repeating coil 60 to ground. Relay 63 is thereupon energized and pulls up its armature, establishing a circuit from grounded battery, through conductor 65, electromagnet 19, conductors (86 and 67 to ground at the armature and front contact of relay 63. Electromagnet 19 is thereupon energized and pulls up its armature 20, which actuates the locking plate 18 against the tension of spring 14;. This looking plate, as previously described, retains the operated push rod 6 in its operated position until the calling subscriber hangs up his receiver. Another circuit. which is established upon the operation of relay 63, may be traced from grounded battery through relay 41, conductor 68, line unit conductor 5 line unit contact spring 5 and trunk unit conductor 1 conductor 67 to ground at the armature and front contact of relay 63. Relay 11 being thereby energized pulls up its armatures and opens the circuit of electromagnet 9, thereby deenergizing the latter and permitting the line bar 7 to be returned to its normal position by spring 43.

Upon the longitudinal movement of shaft 23, previously described, another trunk bar is moved into its preselected position and the trunk bar which was used for establishing the connection just described is returned to its normal position by the operation of rocker member 21, the latter being actuated by the newly selected trunk bar in its upward movement.

The circuit of motor magnet 27 extends fron'i grounded battery through contact springs 56 and 57, conductor 69, magnet 27, conductor 70, contact brush 4E5, contact ring 31, contact brush 30 through any one of the metal contacts 33 and its conductor 71, and thence over one of two paths to ground, namely, through contact springs 72, and 73 when the trunk bar associated therewith is in preselected position as shown at the right of Figure 1, or through contact springs T2 and 74:, and conductor 7 5 to ground at the armature of relay 63 when the trunk bar is in its normal position and the trunk associated therewith is busy. Motor magnet 27 will be actuated to rotate shaft 23 step by step as long as contact brush 3O continues to grounded contacts As soon as 30 finds a contact 33 which is not grounded, in other words, one which is associated with an idle trunk, the circuit of motor n'iagnet 27 will be broken and shaft 2-3 will stop rotating. The. cam 29 associated with the idle trunk thus selected then stands l rt-Wed bell crank 28.

In response to the next incoming call the shaft 23 will be moved in the direction indicated by the arrow in Figure 1, whereupon the connection will be established in the manner previously described, and the shaft will be immediately returned to its normal position. On its return movement it will the bell crank and actuate it to lift the newly selected trunk bar into its preselected position, the operation of selecting another idle trunk is then repeated.

Upon the calling subscriber replacing his receiver on the switchhook. the previously dos: ibed circuit through relay 63 is broken anl its armature falls back, thus breaking the circuit ot electroniagnet 19. The locking plate 18 is then restored to normal by its spring 44, permitting the push rod 6 to return to normal, thus breaking the connection between the subseribefs line and the trunk. The breaking of the contact at the armature of relay 63 also removes ground from contact spring 74, thereby causing the trunk assoc ted therewith to test not busy. The cir- .it of relay 411 is also opened upon the deenergization of relay 63.

That claimed is:

1, In a switch, of contacts, plungers for said other plungers for operating said first nluugers. said plungers normally out of o rahle relation one to another, means for moving said plungers into operable relation one to the other, arms for moving said plungers jointly when they are in operable relation one to another to effect engagements between two of said sets of contacts, and means for locking the first mentioned plungers in operated positions during said engagements independent of said arms and second mentioned plungers.

2. A switch comprising a plurality of contact sets, a plurality of push-rods for said contact sets, two plungers for each of said push-rods, said plungers normally out of operable relation to their associated pushrod and to each other, means operable to move said plungers out of their normal positions into operable relation one to the other and to their associated push-rod, means for jointly moving said plungers to operate their respectively associated pushrod to effect an engagement between two of said contact sets, and means for releasing said plungers without releasing said contact sets.

3. In a line switch, a bank comprising a plurality of sets of contacts arranged in coordinate rows, each set comprising line conductor contacts and trunk conductor contacts, a push rod for each set of contacts, a plurality of line bars, each associated with a row of contact sets in one direction, a plurality of trunk bars, each associated with a row of contact bars in the other direction, said line bars and trunk bars disposed coordinately, to each other, a plurality of plungers on each line bar, each plunger associated with one of said push rods, said line bars normally positioned so that their respective plungers are out of operable relation to said push rods, a plurality of plungers on each trunk bar, each trunk bar plunger associated with one of said line bar plungers, said trunk bars normally positioned so that their respective plungers are out of operable relation to their associated line bar plungers, line bar operating means and trunk bar operating means jointly operable to move any associated pair of said plungers into operable relation one to the other and to their associated push rods, and means operable when any of said plungers are disposed in operable relation to each other to move said associated plungers and push rods to effect operation of the contact sets associated therewith. I

4. In a switch, a plurality of sets of contacts a group comprising a plurality of sets of plungers, the plungers of each set movable together in one direction and individually in a second direction, means for moving said sets of plungers in said first direc-. tion, a second group comprising a plurality of sets of plungers, the plungers of each set of said second group movable together in one direction and individually in a second direction, means for moving the sets of said second group in the first direction, a movement in the first direction of the set of the first group together with a movement in the first direction of a set of the second group effective to operatively associate a plunger of each of said sets one with the other, and means operable to move said operably associated plungers jointly in the second direction to effect operation of one of said sets of contacts.

5. In a line switch, a plurality of trunk bars and a plurality of line bars, a group of multiple trunk contacts associated with each trunk bar, a group of multiple line contacts associated with each line bar, a set of plungers for each trunk bar, a set of plungers for each line bar, means for preselectively moving each of said trunk bars together with its plungers individually, means for moving each of said line bars together with its plungers individually, whereby said line bar plungers may be individually brought into operable relation with individual plungers of preselected trunk bars, and means operable to move jointly any of said trunk bars, and line bar plungers which may be in operable relation one to the other to effect engagement between a line and a trunk contact.

6. In a line switch, a plurality of trunk bars and a plurality of line bars, said trunk bars disposed at right angles to said line bars, a plurality of plungers on each of said trunk bars and a plurality of plungers on each of said line bars, a plurality of sets of contacts each set of contacts operable in response to the joint operation of one of said trunk bar plungers and one of said line bar plungers, means for individually moving each of said line bars together with its plungers out of normal into a position wherein each plunger thereon is in operable relation to one of said sets of contacts, means for individually moving each of said trunk bars ofi normal into a position wherein each of its plungers are engageable with a plunger on each of said line bars when the latter are off-normal, and for imparting a movement to off-normal trunk bar plungers whereby the off-normal line bar plungers associated with said off-normal trunk bar plungers are moved to effect operation of the respectively operated sets of contacts.

7. In an automatic telephone switch, a frame, a plurality of stationary trunk conductor units fixedly attached to said frame but insulated therefrom, a plurality of sets of rigid lugs fixedly attached to each of said trunk conductor units, a plurality of stationary line conductor units extending transversely to said trunk conductor units, fixedly attached to said frame but insulated therefrom, a plurality of sets of resilient members fixedly attached to each of said line conductor units each set being individual to each of said sets of rigid lugs, a push-rod for each of said sets of resilient members, a plurality of plungers for each of said pushrods, and means operable to move the said plungers against said push-rod thereby effecting an engagement between said pushrod and a set of resilient members, said engagement forcing the said set of resilient members into contact with its associated set of rigid lugs. 0

In Witness whereof, I hereunto subscribe my name this 18th day of April A. D., 1921.

EDWVARD B. CRAFT. 

